1. Field of the Invention
A floating caliper type disc brake of the present invention is used for braking an automobile. The present invention provides a disc brake of this type capable of obtaining an excellent brake force over a long period of time and preventing the occurrence of noise by preventing uneven wear of pads incorporated into the disc brake.
2. Description of the Related Art
For example, as disclosed in Japanese Patent No. 2779027, there is provided a conventional disc brake for braking an automobile, which is called a floating caliper type disc brake, in which the caliper is displaced with respect to the rotor during braking. This floating caliper type disc brake is composed in such a manner that the support member arranged adjacent to the rotor, which is rotatable together with the wheel, is fixed to a vehicle body, and the caliper is movably held by the support member so that the caliper can be freely displaced in the axial direction of the rotor. Both end sections of a pair of pads are slidably engaged at positions separate from each other in the circumferential direction of the rotor in a portion of the support member so that both end sections of the pair of pads can be freely slid in the axial direction of the rotor. The caliper having a cylinder and pawls arranged across the pads, and the cylinder houses a piston for pushing the pad against the rotor.
In the case of braking, pressure fluid is supplied into the cylinder, and the pad on the inner side is pushed against the inner face of the rotor. Then, the caliper is displaced by the reaction of this pushing force. Therefore, the pawls push the pad against the outer face of the rotor. As a result, the rotor is strongly held by both sides of the inner and the outer face, so that braking can be conducted.
In the conventional floating caliper type disc brake, which is disclosed in Japanese Patent No. 2779027, the pad is minutely displaced together with the caliper in a direction except for the axial direction of the rotor which is the original direction of displacement. As a result, the pad tends to behave unstably. When the pad behaves unstably as described above, the lining composing the pad wears unevenly with respect to the direction of the face. That is, what is called uneven wear is caused, and further the pad is vibrated in the braking operation, and noise offensive to the ear tends to be caused.
The present invention has been accomplished in view of the above circumstances. It is an object of the present invention to prevent the occurrence of uneven wear of the lining composing the pad by stabilizing the behavior of the pad during braking, and also it is an object of the present invention to prevent the occurrence of noise during braking.
In the same manner as that of the conventional floating caliper type disc brake, the floating caliper type disc brake of a first aspect of the present invention includes: a support member, run-in side and run-out side support engaging sections, a pair of pads, a caliper and a piston.
The support member is held by a vehicle body being located adjacent to a rotor rotating together with a wheel.
The run-in side and run-out side support engaging sections are respectively provided in a run-in side and run-out side end sections of the support member. Each of the pads is arranged on one face of a back plate opposing to the side of the rotor and provided with a lining. Run-in side and run-out side pad engaging sections, which are arranged at both end sections of the back plate, are engaged with the run-in side and run-out side support engaging section so that the run-in side and run-out side pad engaging sections can be freely slid in the axial direction of the rotor. Under the above condition, the run-in side and run-out side pad engaging sections are arranged opposing to both sides of the rotor.
The caliper is held by the support member being freely displaced in the axial direction of the rotor.
The piston is housed in the caliper and freely pushed out toward the rotor according to supply of pressure fluid into the caliper.
Braking is conducted when the pair of pads are pressed against both sides of the rotor by the caliper according to the pushing motion of the piston.
A relation between the distance of the run-in side and run-out side support engaging sections and the distance of the run-in side pad engaging section and the run-out side pad engaging sections is restricted. When the relation between both the distances is restricted, at least one of the pair of pads is beared by the support member only with one of the support engaging sections of the run-in side and the run-out side support engaging sections when the brake torque according to a frictional force caused between the side of the rotor and the lining of the pad is not higher than a predetermined value. At least one of the pair of pads is beared by the support member with both the run-in side and the run-out side support engaging sections when the brake torque according to a frictional force caused between the side of the rotor and the lining of the pad exceeds the predetermined value.
Especially, in the floating caliper type disc brake of the present invention, the run-in side and run-out side support engaging sections are respectively formed into a substantially L-shaped engaging protrusion composed of a rising section arranged in the radial direction of the rotor and a bent section bent at a tip end of the rising section in the circumferential direction of the rotor, and the run-in side and run-out side pad engaging sections are respectively formed into a substantially L-shaped engaging groove corresponding to the L-shaped engaging protrusion. In the engaging condition of each engaging protrusion with each engaging groove, the rising section composes a brake torque bearing section for preventing the pad from being displaced in the circumferential direction of the rotor together with the rotor when brake torque is generated, and the bent section composes a rotation preventing section for preventing the pad from being rotated by a couple of forces.
According to the floating caliper type disc brake of the present invention composed as described above, it is possible to stabilize the behavior of the pad during braking. Therefore, the occurrence of uneven wear of the lining composing the pad can be prevented, and further the occurrence of noise can be prevented when the brake is applied.